Question 1

The vitamin pantothenic acid is involved in this type of reaction:

Accepted Answer

A)   Carboxylation reactions
B)   Decarboxylation reactions
C)   Redox reactions
D)   Acyl transfer reactions
E)   Transamination reactions

Question 2

Homotrophic effects for allosteric enzymes involve

Accepted Answer

A)   the same molecule binding to different sites in the enzyme.
B)   different molecules binding to the same site in an enzyme.
C)   different molecules binding to different sites in the same enzyme.
D)   All of these are homotrophic effects.

Question 3

Which groups of amino acids are most likely to be found in the active site of an enzyme?

Accepted Answer

A)   leucine, lysine, alanine.
B)   cysteine, isoleucine, phenylalanine.
C)   tyrosine, threonine, leucine.
D)   serine, histidine, aspartate.

Question 4

A transition-state analog is likely to bind to an enzyme

Accepted Answer

A)   more tightly than the substrate.
B)   less tightly than the substrate.
C)   about as tightly as the substrate.
D)   at a site other than the catalytic site.

Question 5

Metal ions play an important role in reaction mechanisms because

Accepted Answer

A)   they block the active site of enzymes so that inhibitors cannot bind.
B)   they can act as Lewis acids.
C)   water is excluded from the active site when metal ions are bound.
D)   they prevent protein aggregation.

Question 6

The active site of chymotrypsin contains all of the following, except :

Accepted Answer

A)   Histidine residue.
B)   A magnesium ion.
C)   Hydrophobic pocket to bind the substrate.
D)   Serine residue.
E)   All of these are in the active site of chymotrypsin.

Question 7

​ What is the advantage of the sequential model over the concerted model for allosteric enzymes?

Accepted Answer

The concerted model is simple and descri...

Question 8

Exhibit 7A  Refer to Exhibit 7A. Which two enzymes would be the most likely ones to regulate if this pathway is freely reversible and can go both ways?

Accepted Answer

A)   1 and 2
B)   1 and 3
C)   1 and 5
D)   2 and 4
E)   4 and 5

Question 9

Which of the following statements about coenzymes is true ?

Accepted Answer

A)   They are commonly derived from vitamins.
B)   They bind to the active site region on specific types of enzymes.
C)   They can be metal ions, such as Zn(II) .
D)   NAD+, FAD and biotin are all examples of coenzymes.
E)   All of these statements are true.

Question 10

Phosphorylation of enzymes

Accepted Answer

A)   has no effect on their catalytic activity.
B)   does not require ATP.
C)   usually takes place on serine, threonine, and tyrosine residues.
D)   always increases the activity of the enzyme

Question 11

Redox reactions often use this cofactor:

Accepted Answer

A)   Riboflavin
B)   Lipoic acid
C)   Pyridoxal
D)   Thiamine
E)   Biotin

Question 12

Which of the following is not true about B vitamins?

Accepted Answer

A)   They are usually fully active in the form we eat them
B)   They are usually water soluble
C)   Niacin and riboflavin are examples
D)   They are important in many metabolic reactions

Question 13

Which of the following is true about caspases?

Accepted Answer

A)   they are a class of proteases
B)   they are involved in apoptosis
C)   they are initially produced as inactive procaspases
D)   once activated, they attach specific targets leading to cell death
E)   all of these

Question 14

How are cofactors bound to their enzymes?

Accepted Answer

A)   always covalently
B)   always non-covalently
C)   either covalently or non-covalently
D)   via linking with a metal ion
E)   none of these

Question 15

Which of the following is an advantage of an allosteric drug compared to an orthosteric one?

Accepted Answer

A)   they can modulate their effect in a more subtle way
B)   an allosteric drug may be more specific for a specific reaction than one that binds to the receptor itself
C)   they may be safer as they have no effect at all unless the natural substrate is present
D)   all of these are advantages
E)   none of these is an advantage

Question 16

Which of the following enzymes is not a serine protease?

Accepted Answer

A)   trypsin
B)   chymotrypsin
C)   thrombin
D)   aspartyl transcarbamylase (ATCase)

Question 17

Acyl transfer reactions often use this cofactor:

Accepted Answer

A)   Riboflavin
B)   Lipoic acid
C)   Pyridoxal
D)   Thiamine
E)   Biotin

Question 18

Which of the following best describes negative cooperativity?

Accepted Answer

A)   Binding of one substrate molecule prevents the enzyme from working at all.
B)   Binding of one substrate molecule inhibits the binding of a second substrate.
C)   Binding of one substrate molecule enhances the binding of a second substrate.
D)   Binding of one substrate molecule inhibits the binding of other effectors.

Question 19

Allosteric enzymes must exhibit which of the following?

Accepted Answer

A)   feedback inhibition
B)   a phosphorylation site
C)   general acid-base catalysis
D)   a quaternary structure
E)   none of these must be exhibited

Question 20

The sequential model for allosteric enzymes was proposed by:

Accepted Answer

A)   Koshland
B)   Pauling
C)   Pasteur
D)   Monod, Wyman and Changeux
E)   All of these

Exam 7: The Behavior of Proteins Enzymes Mechanisms and Control

Redox reactions often use this cofactor:

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Which of the following enzymes is not a serine protease?

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A transition-state analog is likely to bind to an enzyme

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The active site of chymotrypsin contains all of the following, except :

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The sequential model for allosteric enzymes was proposed by:

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Which of the following best describes negative cooperativity?

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Allosteric enzymes must exhibit which of the following?

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Which of the following is true about caspases?

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Acyl transfer reactions often use this cofactor:

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Metal ions play an important role in reaction mechanisms because

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Which of the following statements about coenzymes is true ?

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How are cofactors bound to their enzymes?

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Which of the following is not true about B vitamins?

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Phosphorylation of enzymes

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Exhibit 7A Refer to Exhibit 7A. Which two enzymes would be the most likely ones to regulate if this pathway is freely reversible and can go both ways?

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Which of the following is an advantage of an allosteric drug compared to an orthosteric one?

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​ What is the advantage of the sequential model over the concerted model for allosteric enzymes?

Correct AnswerverifiedThe concerted model is simple and descri...View AnswerShow Answer

The vitamin pantothenic acid is involved in this type of reaction:

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Homotrophic effects for allosteric enzymes involve

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Which groups of amino acids are most likely to be found in the active site of an enzyme?

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What is the advantage of the sequential model over the concerted model for allosteric enzymes?

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The concerted model is simple and descri...
View Answer

Correct Answer
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Correct Answer
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